Corpuscles

Corpuscle is a general term used to denote a small, discrete body in science. The word, derived from Latin corpusculum meaning "a small body," has been applied across disciplines to refer to microscopic particles, cells, or sensory or structural units. In modern usage, the meaning depends on context and may range from blood cells to renal structures to skin receptors.

In biology, "blood corpuscles" historically referred to the cellular components of blood—red blood cells (erythrocytes) and white blood cells (leukocytes). The renal corpuscle is a unit of the kidney comprising the glomerulus and Bowman's capsule, where blood filtration begins.

Several mechanoreceptors in the skin are named corpuscles, including Pacinian corpuscles (deep pressure and vibration) and Meissner's corpuscles (light touch); other end organs such as Krause end bulbs and Merkel discs are also described as corpuscular receptors in some classifications.

In physics, corpuscular theory posited that light and matter consist of tiny particles (corpuscles). Isaac Newton advocated a corpuscular theory of light; this view was superseded by wave theory, though modern quantum theory reintroduces particle aspects, with photons as the quantum of light. The term "corpuscular radiation" has also referred to alpha and beta particles.

The term remains in use mainly in anatomical contexts (renal and sensory corpuscles) and in historical discussions of physics, rather than as a general scientific category.